Rationale: Proteins released from muscle during and shortly after exercise, often referred to as myokines, may be central to our understanding of the cross-talk during and after exercise between skeletal muscles and other organs, in particular the liver. So far only a few myokines are identified (e.g. IL-6, IL-8, IL-15, TNF-alpha). Taking into account the role of these several known myokines in developing insulin resistance, revealing new putative myokines might provide valuable information and a direction for future research on the pathogenesis and treatment of type 2 diabetes mellitus.